Vinod N. Dhage

Influence of Nd:YAG laser irradiation on AC impedance and dielectric properties of lithium ferrite

Polycrystalline samples of Li0.5Fe2.5O4 spinel ferrite have been synthesized by a standard ceramic technique. The samples were irradiated with an Nd:YAG laser to study the effect of laser irradiation on the structural, dielectric and AC impedance properties. The X-ray diffraction results show the formation of a disordered cubic structure after irradiation. The dielectric constant (ϵ′), dielectric loss (ϵ″) and the loss tangent (tan δ ) were measured at room temperature as a function of frequency (f=20 Hz–1 MHz) for the irradiated and unirradiated samples of Li0.5Fe2.5O4 spinel ferrite. The dielectric constant of the irradiated samples is decreased in magnitude compared to the unirradiated samples. It was found that laser irradiation increases the polarization and the resistivity of the samples as a result of electronic rearrangement and lattice defects. The AC conductivity of the samples was derived from the dielectric constant and loss tangent data. The change in AC conductivity is attributed to the creation of lattice vacancies after laser irradiation. The AC impedance analysis was used to separate the grain and grain boundary of the Li0.5Fe2.5O4 spinel ferrite.

Effect of Gamma Irradiation on the Physical Properties of Nanocrystalline Li0.5Fe2.5O4

The ferrite nanoparticles of Li0.5Fe2.5O4 spinel ferrite was synthesized by sol‐gel auto‐combustion technique using the nitrates of the respective cations at low temperature with a final pH 8. A part of as prepared powder was sintered at 700° C for 6 h and treated as the precursor for the gamma irradiation study. The damage investigations were evaluated on the basis of X‐ray diffraction and SEM techniques. The X‐ray diffraction data was used to investigate the phase purity and structural properties of the synthesized lithium ferrite. The lattice constant of studied samples were increased whereas crystallite size and grain size decreased after gamma irradiation.

Effect of Al3+‐Cr3+ Substitution on Structural, Cation Distribution and Magnetic Properties of MgFe2O4 Prepared by Chemical Co‐precipitation Method

The low temperature synthesis of Al‐Cr substituted MgFe2O4 ferrite system have been carried out using chemical co‐precipitation technique at 60 °C. The nanocrystallites of MgAlXCrXFe2−2XO4 ferrite system were characterized by X‐ray diffraction technique. The X‐ray diffractometer (XRD) showed the formation of single phase cubic spinel structure. Energy dispersive analysis of X‐rays (EDAX) showed the composition close to stichiometry of Al‐Cr substituted MgFe2O4. The most intense peak (311) of XRD patterns was used to calculate crystallite size of the samples and the crystallite size was found to be about 30 nm. The cation distribution which depends on the method of preparation and chemical composition has been determined by using XRD method. The saturation magnetization and magneton number obtained from hysteresis loop technique decreases as Al‐Cr content x increases. The decrease in magnetic behavior is attributed to decrease in A‐B interaction.

Structural and Magnetic Characterization of BaFe12O19Nanoparticles

Barium hexaferrite nanoparticles have been synthesized successfully by using sol‐gel auto‐combustion technique. In this process dextrose and citric acid both used as a fuel separately. The ratio of cation to both the fuel was maintained at 1:3 whereas the pH of the sample was kept constant at 8. The particle size for dextrose and citric acid sample is 34 nm and 45 nm respectively. The room temperature hysteresis curve gives maximum magnetization (48.46 emu/g) and coercivity (1.350 kOe) values for dextrose used sample. The dextrose used sample gives better results than that of citric acid used sample.

Structural and Magnetic Characterization of BaFe[sub 12]O[sub 19] Nanoparticles

Barium hexaferrite nanoparticles have been synthesized successfully by using sol‐gel auto‐combustion technique. In this process dextrose and citric acid both used as a fuel separately. The ratio of cation to both the fuel was maintained at 1:3 whereas the pH of the sample was kept constant at 8. The particle size for dextrose and citric acid sample is 34 nm and 45 nm respectively. The room temperature hysteresis curve gives maximum magnetization (48.46 emu/g) and coercivity (1.350 kOe) values for dextrose used sample. The dextrose used sample gives better results than that of citric acid used sample.

Structural and Magnetic Characterization of BaFe12O19 Nanoparticles

Barium hexaferrite nanoparticles have been synthesized successfully by using sol‐gel auto‐combustion technique. In this process dextrose and citric acid both used as a fuel separately. The ratio of cation to both the fuel was maintained at 1:3 whereas the pH of the sample was kept constant at 8. The particle size for dextrose and citric acid sample is 34 nm and 45 nm respectively. The room temperature hysteresis curve gives maximum magnetization (48.46 emu/g) and coercivity (1.350 kOe) values for dextrose used sample. The dextrose used sample gives better results than that of citric acid used sample.